The present invention relates to testing apparatuses used to test components of a motor vehicle. More particularly, the present invention relates to a testing apparatus used to test tire, wheel, spindle and/or braking components of a motor vehicle, for instance, specifically wheel fatigue and wheel lug nut retention.
A rolling wheel testing apparatus using the inside of a rotating drum was developed by the Fraunhofer-Institut Fur Betriebsfestigkeit and has been shown to be an effective test technique. Generally, a tire and wheel assembly is mounted to a drive motor and is disposed within a drum where the tire engages an inside circumferential surface. Improvements have been made on the original design to simulate loading when the tire and wheel assembly is mounted to a motor vehicle as the motor vehicle travels down a road. The loading can include radial wheel loading to simulate the weight and dynamic loading of the vehicle and lateral loading where the load is applied along the axis of rotation of the tire and wheel assembly. In yet further embodiments, applications of driving and braking torque have also been proposed in xe2x80x9cAdapting the Biaxial Wheel Test System for Brake Components and Lug-Looseningxe2x80x9d, published in the Proceedings of the 3rd International User Meeting, Sep. 11, 1997, Darmstadt, Germany.
Although the original design has been found effective and improvements have been made to simulate road conditions, shortcomings are still present. For instance, accurate simulation of the torque loading upon the tire and wheel assembly as the motor vehicle initially accelerates from a standing stop is lacking. Secondly, although proposed apparatuses use production brake caliber designs, other brake system components are not included.
In addition, it is desirable to install strain gauges and/or other sensors to measure various parameters of the wheel as it rotates within the drum. However, in view that the wheel rotates within the drum, extracting the signal data is, at best, challenging. Although radio transmitters and associated receivers can be used to obtain this information, this technique is considered unsatisfactory in view that a considerable amount of electric noise is present during operation.
An improved rolling wheel testing apparatus that addresses one, some or all of these concerns is therefore desired.
An apparatus and method of operating a rolling wheel testing apparatus includes driving a tire and wheel assembly about an axis of rotation with a tire in rolling contact with a rotatable drum. Torque is sensed about the axis of rotation and rotation of the drum is inhibited so as to develop a selected amount of torque about the axis of rotation as the tire and wheel assembly is rotated.